Whedon might sit behind the lens for the upcoming two-part episode due next year, reports aceshowbiz.com.

He is credited with directing two Marvel movies, “The Avengers” and “Avengers: Age of Ultron”.

He also has a history with musicals, having helmed the “Buffy the Vampire Slayer” musical episode “Once More, With Feeling”, a “Glee” episode “Dream On” and “Dr. Horrible’s Sing-Along Blog”. The latter two feature Neil Patrick Harris.

The songs are still kept secret, but executive producer Greg Berlanti has said they “have been talking about trying to write at least one original song per episode.”

While details of the crossover are still scarce, Music Meister (Batman character) is rumoured to be the villain and Harris who voiced the character in “Batman: The Brave and the Bold” animated series might reprise his role.